1. Accurate Model Measuring in D-Cad
Prepared by
Drs Jeffery Taylor and David Dana

2. YOU need a mouse if you only have a touch pad!
Using a touch pad is not accurate to place the points
Use a Mouse!

3. Typical Scan of upper arch, anterior segment

4. Note contact point shown by arrow

5. Now note point of transition from incisal edge to proximal surface

6. Here are the same points shown in black and white respectively, same model rotated to show incisal edge view

7. Most common error is to locate DentCad points at the white locations when they should be at the black ones.

10. Zoom view of same Dcad file

11. With tooth outlines moved
NOT HERE
Place point here

13. Incorrect point placement =
Incorrect tooth size, incorrect amount of crowding, inadequate vto, and wrong loop size selection
AND MOST IMPORTANT INCORRECT DIAGNOSIS AND TREATMENT PLAN

14. Model analysis
It is extremely important that the model analysis represent what you see clinically
If you see 5 mm crowding, then the model analysis should have 5 mm crowding

15. Example
This case has 10mm crowding on the lower and 10 mm on the upper

16. Arch wire was placed correctly, on the incisal edges, and points were placed incorrectly making the analysis to show 2mm crowding lower and 0 upper

17. This is the most common error made
Not to confirm that the model represents what is seen clinically
Points should be at the widest mesi-distal width of the tooth
If the teeth have contact points the vectors should touch each other

18. The arrows mark areas of incorrect point placement

19. The widest part of the bicuspids is not at the central grove -it is at the buccal line angles
Notice the incisors vectors in blue contacting (same as the teeth)

20. The real point is the white center in the blue dot, not the edge of the Blue/Green dot

21. If the incisors have a normal contact the mesial and distal dots will overlap
Notice 31 and 41 points are on top of each other as they share a contact that is not broken

22. VTO OBTAINED FOR INCORRECT MODEL ANALYSIS
LEADING TO INCORRECT DIAGNOSIS

23. After alignment the incisors advance a significant amount and plan had to be changed to extraction

24. Accurate model measurement lead to accurate VTO

25. Incorrect model = incorrect Correct model = VTO Correct VTO

27. Therefore the moral of the story is to place the points for the incisors on a line bisecting the incisal edge but at the point in space representing the contact point. In this way you will tell the software the actual width of each incisor. This is very important to obtain accurate data that you will receive from DentalCad. Confirm the measurements before proceeding